The present invention relates to a brushless direct current fan, and particularly to a bearing system for brushless direct current fans.
Direct current fans are often used in small-size electrical appliances such as a personal computer. A direct current fan includes a rotor, a stator, and a frame supporting the rotor and the stator. The rotor is rotatably mounted on the stator by means of a bearing system. The bearing system includes a shaft axially mounted on the rotor, a plurality of bearings rotatably holding the shaft, and a bearing pedestal tightly receiving the bearings.
As the bearing pedestal is formed by injection molding, the formed bearing pedestals could possibly produce a misalignment after long-term utilization. Thus, an off center is induced between the bearings, greater abrasion between the shaft and inner walls of the bearings will occur when the shaft rotates.
Further, as the bearings have to be tightly fitted in the bearing pedestal, the bearing pedestal has to be superior in shape accuracy and size accuracy. And, as the bearing pedestal is integrally formed with the frame, if a misalignment is presented in the bearing pedestal, the frame will be considered defective and not suitable for utilization.